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Патент USA US3068537

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Dec. 18, 1962
Original Filed Jan. 22, 1959
United States Patent vf?ce
Patented Dec. 18, 1962
or ?lm-like. Usually, in any mass of ?brids, the indi
vidual ?brid particles are not identical in shape and may
include both ?ber-like and ?lm-like structures. The non
Paul Winthrop Morgan, West Chester, Pa., assignor to
rigid characteristic of the ?brid, which renders it extreme
ly “supple” in liquid suspension and which permits the
physical entwinement described above, is presumably due
E. I. du Pont de Nemours and Company, Wilmington,
DeL, a corporation of Delaware
Original application Jan. 22, 1959, Ser. No. 788,371, now
Patent No. 2,999,788, dated Sept. 12, 1961. Divided
to the presence of the “minor” dimension.
and this application .ian. 4. 1960, Ser. No. 380
6 Claims. (Cl. 18-48)
this dimension in terms of denier, as determined in ac
cordance with the ?ber coarseness test described in Tappi
10 41, l75A-7A, No. 6 (June) 1958, ?brids have a denier
This invention relates to a composition of matter and
to a process for its production. More speci?cally it re
no greater than about 15.
lates to a method of producing a novel and useful non
heterogeneous and odd-shaped structures are di?icult to
express. Even screening classi?cations are not always
Complete dimensions and ranges of dimensions of such
rigid, wholly synthetic polymeric particle as described
more in detail hereinafter which is particularly useful in 15 completely satisfactory to de?ne limitations upon size
since at times the individual particles become entangled
the production of sheet-like structures.
with one another or wrap around the wire meshes of the
0bjects.—It is an object of the present invention to
screen and thereby fail to pass through the screen. Such
provide a novel, non-rigid, wholly synthetic polymeric
behavior is encountered particularly in the case of ?brids
particle of ‘matter capable of forming sheet-like structures
on a paper-making machine.
Another object is to provide a method by which a
made from soft (i.e., initial modulus below 0.9) poly
Hard polymers (i.e., initial modulus above 0.9
novel, non-rigid particle of a synthetic polymer, useful in
g./denier) are more readily tested.
the production of non-woven structures, can be made di
however, ?brid particles, when classi?ed, according to the
Clark Classi?cation Test (Tappi 33, 294-8, No. 6 (June)
rectly from polymer intermediates.
As a general rule
These and other objects will become apparent in the 25 1950) are retained to the extent of not over 10% on a
IO-mesh screen, and retained to the extent of at least
course of the following speci?cation and claims.
90% on a ZOO-mesh screen.
Statement of lnventi0n.—The present invention pro
Fibrid particles are usually frazzled, have a high spe
vides a process for the production of a novel and useful
non-rigid, wholly synthetic polymeric particle which
ci?c surface area, and as indicated, a high absorptive ca
process comprises shredding, in a liquid suspension the 30 pacity for water.
Preferred ?brids are those the waterleaves of which
gel structure produced by the interfacial forming tech
nique (US. Patent 2,708,617). The novel, non-rigid
polymeric particle of this invention, hereinafter referred
to as a “?brid,” is capable of forming paper-like struc
when dried for a period of twelve hours at a temperature
below the stick temperature of the polymer from which
they are made (i.e., the minimum temperature at which
about 0.002 gram per denier when a plurality of the said
a sample of the polymer leaves a wet molten trail as it
is stroked with a moderate pressure across the smooth
surface of a heated block) have a tenacity of at least
about 0.005 gram per denier.
particles is deposited from a liquid suspension upon a
Identi?cation of Figures.-——The invention will be more
tures on a paper-making machine. To be designated a
“?brid,” a particle must possess (a) an ability to form
a waterleaf having a couched wet tenacity of at least
screen, which waterleaf, when dried at a temperature 40 readily understood by reference to the ?gures.
Figures I and II illustrate typical technique embodi
below about 50° C., has a dry tenacity at lea-st equal to
ments suitable for use in the process of the present in
its couched wet tenacity and (b) an ability, when a plu
vention. Each of the ?gures is described in greater de
rality of the said particles is deposited concomitantly with
tail below.
staple ?bers from a liquid suspension upon a screen, to
bond a substantial weight of the said ?bers by physical
entwinement of the said particles with the said ?bers to
give a composite waterleaf with a wet tenacity of at least
about 0.002 gram per denier. In addition, ?brid parti
cles have a Canadian ‘freeness number between 90 and
790 and a high absorptive capacity for water, retaining '
at least 2.0 grams of water per gram of particle under a
compression load of about 39 grams per square centi
meter. By “wholly synthetic polymeric” is meant that the
?brid is formed of a polymeric material synthesized by
man as distinguished from a polymeric product of nature
or derivative thereof.
Fibrid Pr0perzies.—Any normally solid Wholly syn
thetic polymeric material may be employed in the pro
duction of ?brids. By “normally solid” is meant that
the material is non-?uid under normal room conditions.
By “. . . an ability to . . . bond a substantial weight
of . . . (staple) ?bers . . .” is meant that at least 50%
by weight of staple based on total staple and ?brids can
be bonded from a concomitantly deposited mixture of
staple and ?brids.
It is believed that the ?brid characteristics recited
above are a result of the combination of the morphology
Fibrid Production-The method for producing ?brids
described and claimed in the present application consists
in the beating of a liquid suspension of the wet or gel
structure produced by an interfacial forming process. In
the interfacial forming process an interphase polymeriza
tion is conducted between fast-reacting organic condensa
tion polymer-forming intermediates at an interface of
controlled shape- between two liquid phases, each of
which contains an intermediate, to form a shaped con
densation polymer. The process is described in United
States Patent 2,708,617. One embodiment of the proc
ess is illustrated in FIGURE 1, In that ?gure reaction
vessel 1 containing one of the fast-reacting organic con
densation polymer-forming intermediates, 2, has a com
plementary intermediate introduced from “supply”
through 1 tube 3, the condensation polymer forming
at the interface of controlled shape 4. The gel product
5 is withdrawn continuously from the interface over
guides 6 and 7 in the form of a collapsed tube, the walls
_ of which are no greater than about 0.020 inch in thick
ness, described and claimed in United States Patent
2,798,283 ?led December 9, 1953. The tearing or shred
ding operation is accomplished by leading the tubular gel
?lament 5, while still wet, into a vessel 3, containing liquid
and non-rigid properties of the particle. The mor
such as Water 9‘, which is being violently agitated by motor
phology is such that the particle is non-granular and has 70 driven stirrer 10. A Waring Blendor is well adapted to
perform this operation. The ?brids 11 form a slurry
at least one dimension of minor magnitude relative to
in liquid 9. In another embodiment of the process,
its largest dimension, i.e., the ?brid particle is ?ber-like
shown in FIGURE II, the thin ?lm formed at the inter
face is shredded to the ?brid form substantially as rapidly
as it forms, simply by locating stirrer 10 near interface
to permit the sample to drain.
4 in vessel 11, which interface forms between polymer
data obtained from this test are expressed as the familiar
After an additional ten
minutes the sample is removed and weighed.
Freeness is determined by Tappi test T227m50. The
forming intermediates 2 and 12. This technique is il
Canadian standard freeness numbers, which represent
lustrated in Example 5 hereinafter. This process, de
the number of ml. of water which drain from the slurry
scribed and claimed in the present application, is useful
under speci?ed conditions.
in preparing ?brids from any condensation polymer, ei
Elmendorf tear strength is measured on the Elmen
ther linear or cross-linked, which can be formed by in
dorf tear tester according to the procedure described in
terfacial forming. The gel structure is destroyed on dry 10 Tappi test T414m49. The strength recorded is the num
ing of the interfacially formed structure and thereafter‘
ber of grams of force required to propagate a tear the
the structure will not form ?brids when beaten in liquid
remaining distance across a 63 mm. strip in which a 20
suspension as taught herein.
mm. standard out has been made.
Test pr0ce‘dures.—The surface area of hard polymers
Tear factor is calculated by dividing the Elmendorf
is determined by a technique based upon the adsorption
tear strength in grams by the basis weight in g./m.2.
of a unimolecular layer of a gas upon the surface of the
Tongue tear strength is determined in accordance with
sample while it is being maintained at a temperature close
ASTM D-39.
to the condensation temperature of the gas. Because of
Burst strength is measured on the Mullen burst tester
the excellent bonding properties of ?brids, the surface
according to the procedure described in Tappi test
area measurement is dependent to some extent upon the 20 T40m53.
method of handling the sample prior to making the
Fold endurance is determined by Tappi test T423m50,
measurement. Accordingly, the following standardized
using the MIT Folding Endurance tester.
procedure has been adopted. The ?rst step is to wash
Elastic recovery is the percentage returned to original
the ?brids thoroughly with distilled water to remove
length within one minute after the tension has been
all traces of residual solvent. It is preferable to carry 25 relaxed from a sample which has been elongated 50% at
out the washing on a coarse sintered glass funnel. Dur
the rate of 100% per minute and held at 50% elonga~
ing the washing a layer of liquid is maintained over the
tion for one minute.
?brid mat at all times until the very last wash. The vac
Stress decay is the per cent loss in stress in a yarn one
uum is disconnected as soon as the water layer passes
minute after it has been elongated to 50% at the rate
through the mat as this last Wash is completed. The
of 100% per minute.
?lter cake is then dried at 35° C. for at least twelve hours
Initial modulus is determined by measuring the initial
followed by removal of the last traces of air and liquid
slope of the stress-strain curve.
by heating at 50° C. for at least one hour under vacuum
The following examples are cited to illustrate the in
until a pressure as low as 10*3 mm. has been reached.
The bulb containing the evacuated sample is immersed 35
in liquid nitrogen and a measured amount of nitrogen
gas is then brought into contact with the sample. The
vention. They are not intended to limit it in any manner.
Example 1
amount adsorbed at each of a series of increasing pres
sures is determined. From these data the volume of
adsorbed gas corresponding to the formation of a uni
molecular layer of nitrogen on the sample can be de
duced, and from the known molecular area of nitro
gen, the speci?c area of the material is calculated. (See:
25.15 ml. of an aqueous solution containing 0.2138
grams of hexamethylenediamine per ml. are mixed with
16.35 ml. of an aqueous solution containing 0.2155 grams
of sodium hydroxide per ml. and the combined solution
Pittsburgh, Pennsylvania.)
thereby forming two phases. A polymer film of poly~
the sheet and strength measured on an Instron tester.
The values are calculated on the basis of a one inch strip.
with a sintered glass bottom and washed well with aqueous
alcohol and water.
Two such preparations, combined in 3 liters of water,
diluted to 100 ml. with water. This is carefully poured
“Scienti?c and Industrial Glass Blowing and Laboratory
Techniques,” pp. 257-283, by W. C. Barr and V. I. An 45 into a beaker containing 100 ml. of a carbon tetrachloride
solution in which 5.88 ml. of adipyl chloride is dissolved,
horn, published by Instruments Publishing Company,
hexamethylene adipamide) i.e. “66 nylon” forms at the
Unless otherwise indicated, the strength of sheet ma
interface. This glm is drawn out continuously over a wet
terials prepared from “hard” polymers is determined by
a modi?cation of Tappi test T205m53 wherein the pulp 50 feed roller at a rate of about 18 ft./min. into a Waring
Blender in which about 200 ml. of ethyl alcohol con
slurry is poured onto a 100-mesh screen to make a sheet
taining 3 ml. of hydrochloric acid is being stirred rapidly.
which is washed with 10 liters of water, removed from
After the process is continued for 2.5 minutes the product
the screen, and dried in an oven with air maintained at
in the Waring Blender is collected on a Buchner funnel
approximately 100° C. One-half inch strips are cut from
To determine the wet strength one-half inch strips are
cut from the dried sheet and placed in water, where
they are soaked for 30 minutes at room temperature.
The wet strength is also measured on an Instron tester
and the results calcuated on the basis of a one-inch Width.
The water absorption of “hard” polymers is measured
by evenly distributing, without compression, at two-gram
sample of the test material in a Buchner funnel (21/2
inch diameter times 13716 inch deep). One hundred ml.
of water containing 0.1 gram of sodium lauryl sulfate
is poured over the sample and allowed to drain by
gravity for about 1 minute.
The funnel is then con
are poured on an 8" x 8” l00-mesh screen in a hand sheet
box, vacuum being applied as soon as the ?brids are
properly suspended in the liquid in the hand sheet box.
After all of the water has been removed, the sheet is
blotted once on the screen.
It is then removed from the
screen, placed between blotters, and rolled with a steel
rolling pin. After the sheet is dried on a paper dryer
at 85° C. for approximately 10 minutes, it has a dry
tenacity of 0.364 grams/denier at a dry elongation of
46% and a wet tenacity of 0.094 gram/denier at a wet
elongation of 33%.
A slurry of the ?brids from which the sheets are made
are observed to have a Canadian Standard freeness of
3/8 inch head of water in the funnel at equilibrium.
120. The surface area is 8.3 m?/g. A ratio of wet to
When water begins to flow into the funnel a No. 11 rub
dry weight of 11.9 is noted when the weight of a sheet
ber stopper weighing 67.4- grams is placed on the sample
formed on a Buchner funnel with the water just drawn
with the large ‘face down. A two-pound weight is placed
out is compared with the weight of the same sheet dried
on the stopper. After ten minutes the petcock is turned 75 to constant weight at room temperature.
nected to an over?owing reservoir so as to produce a
intermediate (e.g., a solution of an organic dicarboxylic
acid halide) together to form a liquid-liquid interface,
controlling the shape of the interface until a shaped poly
mer has formed, and then withdrawing the polymer from
The process of Example 1 is modi?ed by collecting
the interface. Preferably, the polymer is withdrawn con
the withdrawn ?lm in an 800 ml. beaker containing a
tinuously from the interface as a continuous self-support
solution of 392 ml. of ethyl alcohol and 8 ml. of con
ing ?lm or ?lament. Tearing or shredding is preferably
centrated hydrochloric acid. After 10 minutes the ?lm
performed upon the freshly-made shaped structure. This
is chopped into lengths approximately one inch long
is conveniently done by leading the ?lm or ?ber direct
which are added to the Waring Blendor containing the
into a suitable shredder, as shown in Examples 1 and
solution as described in Example 1, the said blendor 10 ly
3. Alternatively the interfacially spun structure may be
being operated at full speed. After 2 minutes the ?brids
collected and stored in the wet state between the spin
formed are ?ltered o? on a fritted glass Buchner funnel.
ning and shredding operation, as shown in Example 2.
A 1.8 gram sample of the above is washed well and
Another suitable procedure is to withdraw the ?lm formed
suspended in approximately 3 liters of water and a sheet
at the interface in consecutive batches, which are then
formed in a hand sheet box and thereafter ?nished as
shredded or beaten, rather than to remove the interfacial
described in Example 1. The sheet has a dry tenacity
ly-formed structure continuously. When operating in
of 0.255 gram/ denier at a dry elongation of 27% and a
manner the interfacially-formed ?lm may be gently
wet tenacity of 0.059 gram/denier at a wet elongation
agitated to increase its thickness and thereafter shredded
of 18%. The ratio of wet to dry weight is 15.
20 in a liquid suspension. In another modi?cation of this
Example 2
The ?brids have a surface area of approximately 7.3
process, the thin ?lm formed at the interface is shredded
to the ?brid form substantially as rapidly as it forms.
Agitation is controlled to avoid dispersing one reactant
m.2/g. An aqueous suspension of these ?brids has a
Canadian Standard freeness of 154.
Example 3
containing phase in the other prior to formation of the
25 interfacial ?lm.
Example 5
The technique of Example 1 is followed, using a solu
tion of 8 ml. of sebacyl chloride (“10 acid”) in 632 ml.
of carbon tetrachloride as one phase and, as a second
phase, a solution formed by mixing 21.62 ml. of an
aqueous hexarnethylenediarnine (“6 amine”) solution con
taining 0.202 gram of diamine per ml. with 15.34 ml. of
an aqueous sodium hydroxide solution containing 0.196
Suitable conditions are described in EX
ample 5 below.
DD 0
200 ml. of an aqueous solution containing 9.27 grams
hexarnethylene diamine and 6.4 grams sodium hydroxide
volume of 94 ml. with water. The ?lm, 610 polymer,
are placed in a Waring Blendor jar. The blendor is
started at half speed to permit formation of an interfacial
film and 11.76 ml. of adipyl chloride dissolved in 400
ml. of carbon tetrachloride is added through a powder
which is formed at the interface is fed at the rate of 20
funnel inserted in the cover.
gram of sodium hydroxide per ml., and diluting to a total
The addition is made rap
ft./min. for 5 minutes directly into the Waring Blender
containing a 50/50 mixture of ethyl alcohol and water
idly and the mass of forming polymer stops the stirrer
almost immediately. The blades are freed of the prod
containing 10% by weight of hydrochloric acid. When 4-0 uct with a spatula and stirring of the mass is continued
an aqueous suspension of the product is dewatered on a
for 3 minutes producing the ?brid product.
Buchner funnel a cohesive structure is formed.
The product is isolated and washed thoroughly with
Example 4
alcohol and water. The particles are of a twisted, ragged
and branched ?lmy structure. Strong sheets are pre
pared by drawing down the dispersion of particles on a
sintered glass funnel and drying the mat. The inherent
viscosity of the polymer is 0.80 (m-cresol at 30° C. and
0.5 gram polymer/ 100 ml. solution).
Example 1 is modi?ed to pass the ?lm as a ropelike
mass over a bobbin at 12 ft./min. into the Waring Blendor
operating at about 80% of full speed. Several ?ve gram
batches of ?brids having the appearance of narrow,
twisted, irregular ribbons are prepared by this procedure.
This suspension has a Canadian Standard freeness of U3.
A 3 gram, 8 inch square hand sheet prepared from these
?brids has a dry tenacity of 7.93 lbs./in./oz./yd.2 and a
maximum tongue tear of 0.187 lb./in./yd.2
A hand sheet of the same size and weight is prepared
from a mixture containing 50% by weight of the ?brids
prepared as described above and 50% by weight of 3/ 8
It is necessary, both to facilitate shredding and to ob
tain high strength in sheet products, that the interfacial
ly-spun structure be in a highly-swollen condition when
it is shredded. This is accomplished by beating without
intermediate drying.
The interfacially-formed structure is shredded while
suspended in a non-solvent liquid. Suitable shredding or
shearing media include water, glycerol, ethylene glycol,
acetone, ether, alcohol, etc. A choice of liquid is de
pendent upon the nature of the interfacially-formed struc
ture. Aqueous organic liquid mixtures, such as water
staple. This sheet has a dry tenacity of 4.62 00 glycerol or water-ethylene glycol mixtures, are useful in
lbs./in./oz./yd.2 and a maximum tongue tear of 0.557
the process. Water alone is particularly desirable for
economic reasons and works quite satisfactorily in many
The sheet of ?brids and nylon staple is heated to a
cases. Non-aqueous media are sometimes desirable,
inch, 2 d.p.f. 66 nylon [poly(hexamethylene adipamide)]
temperature of 200° C. while being pressed at about
however, particularly to retard crystallization of the poly
1000 lbs./in.2. A high strength (13 lbs./in./oz./yd.2)
mer as it is shaped. A relatively wide range of viscosities
may be tolerated in the shearing medium.
Shredding of the interfacially-formed structures sus
sheet material having a relatively smooth surface results.
The ?brids appear to have fused uniformly throughout
the sheet product.
As exempli?ed above the interfacial spinning tech
pended in the liquid is conveniently performed by turbu
lent agitation. The design of the stirrer blade used in the
nique produces a structure which can be shredded to 70 "Waring Blender has been found to be particularly sat
form ?brids. Interfacial spinning broadly considered in
volves bringing a liquid phase comprising one condensa
tion polymer-forming intermediate (e.g., a liquid organic
isfactory. Shredding action can be increased by in
troducing suitable ba?les in the mixing vessel, for in
stance, as used in the commercial mixing devices of the
Waring Blendor type. Other types of apparatus, such
liquid phase comprising a coreacting polymer-forming 75 as disc mills, Jordan re?ners, and the like, are suitable.
diarnine or solution of an organic diamine) and another
For a device to be suitable for use in this process, it is
necessary that it be capable of tearing or shredding the
gel structure in the liquid medium‘ to produce ?brous
structures with a minimum su‘face area of above about
cjltulose derivatives, and/or by mixing with beaten cel
4.5 m.2/ g. The mechanical action required to produce
this is, of course, dependent to some extent upon the gel
luwse and/or natural animal ?bers and/ or mineral ?bers.
Many other methods of modifying these slurries are men
tioned elsewhere.
isolation of Fibria's.—~lf it is desired, the ?brids pre
The shredding process forms a slurry of heterogeneous
?brids. The Canadian Standard freeness numbers of 10 pared from hard polymers may be isolated and dried. The
drying conditions required for retention of adequate bond
aqueous slurries of the ?brids obtained by shredding are
ing properties in sheet formation on a papermaking ma
below about 750 and the preferred products of this
chine are not particularly critical, although it is preferable
invention have freeness numbers in the range between
that these conditions not be drastic. For example, the
about 150 and 500. The freeness and many other char
temperature should be kept low enough to avoid fusing the
acteristics of these slurries are similar to those of cellu
swelling factor and the physical form of the polymer
mass to which the shear is applied.
?brids into globular masses, since the bonding roperties
associated with these products would be lost. Also,
severe mechanical action should be avoided, since this
lose pulps used for making paper. They are, therefore,
of particular utility in the manufacture of sheet-like
products on paper-making equipment. As shown in the
would tend to break up the ?brids into fines.
examples above, these sheet-like structures can be made
of ?brids and staple.
More care
in drying ?brids is required if it is desired that they have
bonding properties when redispersed in water identical
from the ?brids alone or may be formed from a mixture
The ?brids bond together to form
with those which they possessed prior to drying.
coherent sheets when settled from liquid suspension, for
One method of drying which has been found suitable
instance, on a screen. Where mixtures of staple and
?brids are deposited, their wet sheets can be handled.
for preparing dried ?brids with adequate bonding proper
ties is to spray-dry a slurry under controlled conditions,
When such sheets, after drying, are subjected to heat
e.g., the temperature should not be too close to the melt
and pressure the ?brids may be fused, as shown in Ex
ample 4. In this way a very strong and uniform sheet
can be produced.
Fibrid Slzeets.—As shown in the previous examples an
important characteristic of ?brids is their cohesiveness
ing point and the slurry which is sprayed should be sub
stantially free of solvent for the polymer. A second
method is to wash the ?brids with a water-miscible low
boiling organic solvent. The water-miscibility require
ment is based on the assumption that the ?brids have
been deposited from an aqueous slurry and are still wet.
or bonding strength in sheet products. This is quite evi
dent in both wet and dry sheets, particularly when the
sheets are compared with the products of the prior art.
For example, the wet tenacity of sheets prepared from
staple ?bers is usually less than 4><10—4 gram/denier.
‘In contrast to this, sheets prepared from “hard” polymer
Another suitable method comprises removing water in
a centrifuge until the moisture content has been reduced
to approximately 100%. The ?brids are then placed in a
cone with an air inlet at the apex.
Air is admitted at
approximately 9 cu. ft./ min. to circulate the ?brids. After
approximately three minutes the moisture content is re
duced to about 50%. The ?uffed ?brids are then trans
?brids have a minimum couched wet tenacity of about
0.002 gram/denier, and frequently have minimum dry
strength, before pressing, of about 0.01 gram/denier. A 40
ferred to an air oven where the moisture content is re
Wet strength of as high as 0.02 gram/denier is not im
duced to approximately 1% by circulating heated air;
usual for these products. The values expressed in
temperatures in the region of 100° C. are usually suitable.
grams/denier may be converted to values expressed as
‘lbs./in./oz./yd.2 by multiplying by 17.
P0lyn'1ers.--Suitable polymers include polyamides, such
as poly(hexamethylene adipamide), poly(ethylene sebac
Redispersion of Fibrids.—The dried ?brids prepared
from “hard” polymers can be redispersed in aqueous
45 media, from which can be made sheet products with sub
stantially the same properties possessed by sheets prepared
directly from the original slurry. Redispersing is usually
antide), poly(methylene bis (polycyclohexylene) adip
amide), polycaprolactam, and copolyamides, such as those
formed from a mixture of hexamethylenediamine, adipic
acid, and sebacic acid, or by a mixture of caprolactam,
hexamethylenediamine, and adipic acid; polyurethanes;
polyureas, polyesters, such as poly(ethylene terepht'na
late); polythiolesters; polysulfonamides; and many others.
Copolymers of all types may be used. Derivatives of the
polymers are also suitable.
Many types of condensation elastomers are also suit
able. United States Patent No. 2,670,267 describes N
a kyl-substituted copolyamides which are highly elastic
and have a suitable low modulus. A copolyamide of this
carried out in an apparatus such as the Hollander heater
and is aided by the use of wetting agents. The process
ing economies of preparing the sheet products from the
original aqueous slurry are obvious, and this is naturally
the preferred method of operation wherever feasible.
However, since it may frequently be necessary to ship the
?brids from the location where they are prepared to an
other location, where they will be converted to sheet prod
ucts, it is a de?nite advantage to be able to dry the prod
ucts to reduce shipping costs.
Fibrid Sheets.—An important characteristic of ?brids
is their cohesiveness or bonding strength in sheet prod
This is quite evident in both wet and dry homo
hexamethylenediamine, N-isobutylhexamethylenediamine, 60 ucts.
sheets. Sheets prepared from “soft” polymer ?brids have
and N.N’-isobutylhexamethylenediamine produces an
a minimum couched wet strength of approximately 0.002
elastomer which is particularly satisfactory for the pur
g.p.d. ‘and a minimum dry strength, before pressing, of
poses of this invention.
approximately 0.005 g.p.d. This exists despite a low level
Free/less Numbers. The freeness numbers of aqueous
of mechanical properties characteristic of the polymers
slurries of ?brids is below about 790‘. The preferred ?
per se, when compared to hard polymers. One char
brids from “hard” polymers have freeness numbers in
acteristic of these sheets, which distinguishes them from
the range between about 100 and about 600. The pre—
homosheet products prepared from hard polymer ?brids
ferred products from “soft” polymers have freeness in the
is their behavior on rewetting after drying. The sheets
type, obtained by reacting adipic acid With a mixture of
range between about 4-00 ‘and about 700.
70 from soft polymer ?brids retain a substantial percentage
The freeness and many other characteristics of fibrid
of the dry strength whereas the upressed, unfused homo
slurries are similar to those of cellulose pulps used for
sheets prepared from hard polymer ?brids drop back
making paper. The primary distinction is that the slur
more nearly to a strength level of the original wet sheet,
ries are prepared from synthetic polymers. Accordingly,
a value which is frequently appreciably lower than the
they may be thought of as synthetic “pulps.” The proper
dry strength. The wet tenacity of sheets prepared from
staple ?bers is usually less than 4X10"4 gram/denier.
modi?ed in many ways. One very practical method of
accomplishing this is to blend the ?brids of this invention
with staple ?bers. These staple ?bers may be derived
Sheets prepared from “hard” polymer ?brids have a mini
mum couched wet tenacity of about 0.002 gram/denier
and a minimum dry strength before pressing of about
0.005 gram/denier. A wet strength of as high as 0.02
gram/ denier is not unusual for these products. Values
expressed as gr-am/ denier may be converted to values ex
from cellulosic materials, staple of synthetic polymers,
or staple ?bers of natural origin. The combination of
?brids with staple generally results in a sheet with higher
tear strength. Within this area the properties can be
controlled or modi?ed by the choice of polymer for pre
pressed as lbs./in./oz./yd.2 by multiplying by 17.
By virtue of their special characteristics, ?brids dis
paring the ?brids, the choice of staple ?ber composition
perse readily to form stable dispersions which may be 10 and/ or length and/ or denier.
used in ordinary papermaking operations without add
The properties of ?brid-bonded sheets, whether they
be homosheets (i.e., all ?brid) or heterosheets, i.e., sheets
ing surfactants. This permits the use of ?brids in paper
making ‘machinery without modi?cation of the usual
from mixtures of ?bers and staple, may be controlled or
processing conditions, and serves to distinguish ?brids
modi?ed by calendering or heating. For example, ?brid
from any previously known ?ber form of synthetic poly 15 homosheets may be made paper-like by calendering alone.
mer. Thus, ?brids may be added to the beater and passed
A wide variety of products may be made by the use of
through the re?ner into the head box onto the screen
of a Four-drinier machine. From there the sheet may
a combination of heat and pressure. The properties ob
tained are controlled by the amount and type (dead
be carried to the wet press through drier rolls, caienders,
load or calender) of pressure applied, calendering tem
and woundup as a sheet without modifying the normal 20 perature, and the like.
operating characteristics of the machines as used for
Urility.-—Products bonded with ?brids have many ap
making cellulose paper. In addition, the papermaking op
plications. One of these is in the form of elastic apparel.
eration can be integrated with ?brid manufacture by col
Such applications include outerwear garments such as
lecting the ?brid on ‘a screen at the exit from the precipi
jackets, coats, skirts, playsuits, under water suits, rain
tation zone. It is also possible to form shaped articles di 25 wear, gloves, watch straps, and in certain shoe applica
rectly from thick ?brid slurries by slush-molding in
tions, such as in house slippers, foot-wear-uppers, and
patterns or molds.
boot and shoe liners. Other apparel and personal items
The advantages of these ?brids in the formation of
include girdles, elastic fabrics for anklets, wristlets, waist—
sheet products becomes more apparent when sheet prod
bands, and sweatbands, handbags, sleeping bags, and
ucts from hard polymers are compared to those from
elastic medical materials, such as surgical and medical
synthetic polymers in the ?ber forms prepared by prior
bandages. Household uses include antiskid mats, such
art processes.
as rug anchors and tub mats, blankets, shower curtains,
Table XVI
and protective covers for such items as coasters, bottles,
Fiber form
drinking glasses, luggage, lamp shades, and the bases of
Wet Sheet 2
Surface area 1
lamps, statues, and silver.
Further applications are in
Wall covering, draperies, and in coated fabrics. They
strength unnress.
unlused ?bers
Hard Polymer
may be used in the manufacture of books, such as in
book binding or covering whether it be the only cover or
above 2.0 ____ __ below 790. above 0.002.
Micro?bers 3_____--__ approximately above 800. Aqueous slurries
and sheets very
dit?cult to form.
Air Jetted Fibers 4.--- 0.5..
Fibers From Fibril1.1.-..
latable Films.
Staple ______________ -_ less than 0.5--- ___do _____ __
N0 greater than
as a protective cover for hard-bound books.
In connec
tion with applications such as this, it is interesting to note
that sheet products made from certain of the elastomer
?brids are heat-scalable.
Use as flannel replacements,
such as in apparel, pool table covers, and phonographic
turn table covers is suggested by the properties of the
45 sheet products.
1 MJ/g.
2 Gr) (1.
3 Fine, round, dense ?bers with a diameter of approximately two
microns or less.
4 Equivalent to those described in U.S. 2,483,405.
An important feature of the bonding properties of
They may be used as linings or inserts,
such as fabric interliners, linings for a variety of cases
such as those used for scienti?c instruments, jewelry,
musical instruments, etc.
Sheet products prepared from hard polymer ?brids,
?brids is that no heat or pressure is required to develop 50 or combinations of these ?brids with hard polymer staple,
adequate strength. The geometry of the sheet is deter
mined primarily by the fcrm in which it is held while
being dried at room temperature. The strength of sheet
products comprising soft polymer ?brids can be increased
have properties which suggest many possible uses. Thus,
the r'ood dimensional stability, excellent resistance to
acids and alkalies, relatively low water absorption, good
Wet strength properties, and resistance to attack by fungus
by heating alone. This is also true to a lesser extent for 55 and mold suggest their use in non-woven products uti
products comprising hard polymer ?brids, but for these
products maximum strength is usually attained by the
lized in such applications as light weight tarpaulins and
tentage material. Other applications outside the usual
combination of heat and pressure.
Pressure rolls and solvent treatments, applied as known
paper and tape uses are as paper drapes and curtains,
in the art, generally tend to produce stiffer, less porous
sheets. Engraved rolls can ‘be used to produce patterns
on these sheets, for example, by forming translucent areas
reinforcements, book covers, both as the sole backing or
as covers for other
types of book bindings. As an ex-.
in an opaque background. Another way of introducing
a texture or pattern on the sheet is to pass it through a
calender which has one roll surfaced with heated ?ne
needles or spikes.
Such a treatment may also serve to
increase the bonding.
Fibrid-Bonded Products-When using ?brids as a
binder in sheet formation, as little as about 1% ?brids
in the ?nal sheet is often highly advantageous. Generally, 70
however, it is preferred to use at least about 5% of the
?brid and at least about 15% ?brid is preferred for maxi
mum strength.
The hand and other properties of sheet products pre
pared from hard and/ or soft ?brids can be controlled and 75
bases for coated fabrics, abrasive backings, diaphrgm
ample of a variety of protective cover applications may
be mentioned covers for military equipment which is be-
ing stored.
An important application for paper-like products is in
the ?eld of bagging, particularly for heavy industrial uses.
However, additional speci?c uses are as vacuum cleaner
bags, shoot bags for pollenation control, sleeping bags,
and tea bags.
Other industrial applications include electrical insula~
tion, transformer press boards, and as wrappings for
underground pipes. They may also be used as wrappings
for food products, such as meat and cheese.
applications include ?lter media, such as ?lter papers,
fuel cells and mold release materials.
1 ‘ti
Sheet products comprising these ?brids are also ideal
ly suited for use as headliners in automobiles, interliners
for non-woven fabrics, and reinforcing agents for rubber
goods, such as belting and tires. Fabric-like sheets of
a cashmere or suede type are formed by brushing a nap
on a sheet containing ?brids from either hard or soft
polyme .
2. The process or” claim wherein the interfacially spun
product in the form of a collapsed tube is continuously
led from its interfacial spinning device to a shredding
3. The process of claim 2 wherein the said shredding
liquid is water.
4-. The process of claim 1 wherein the said interfacially
formed structure is a polyamide.
Many equivalent modi?cations will be .apparent to
5. The process of claim 4 wherein the said polyamide
those skilled in the art from a reading of the above
without a departure from the inventive concept.
10 5-; polyl'lexamethylene adiparnide.
6. The process of claim 4 wherein the said polyarnide
This application is a division of United States applica—
tion 788,371, ?led January 22, 1959, now Patent No.
What is claimed is:
l. A process for the production of a ?brid slurry
which comprises the steps of forming a shaped gel struc
ture of an organic condensation polymer by an inter
phase polymerization between fast-reacting organic con
densation polymer-forming intermediates at an interface
of controiled shape between two liquid phases, each of
which contains
intermediate and beating a liquid sus
pension of the shaped structure so formed prior to drying
the said shaped structure.
is polyhexainethylene sebacarnide.
lileferences'uieo in the ?le of this patent
Magat ______________ __ May 17,
Magat _______________ __ July 9,
Vt’ooding ____________ __ Oct. 22,
Rasmussen ___________ __ Oct. 4,
Great Britain ________ __ Apr. 20,
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